Sweet itch (insect bite hypersensitivity) in horses causes severe year-round suffering in affected animals. By 2026, allergen-specific immunotherapy is emerging as a treatment that addresses the underlying immune hypersensitivity rather than merely managing symptoms, potentially transforming welfare outcomes for affected horses.
Horses with sweet itch experience pruritus so intense that they rub against fences, trees, and posts until bleeding. Chronic rubbing causes hair loss, skin thickening, secondary bacterial infection, and scarring that is painful beyond the allergic itch itself. Full-body management regimes require horses to wear heavy rugs for up to 18 hours per day during summer, restricting thermoregulation and causing heat stress in warm weather. Immunotherapy addressing the root immune dysregulation offers hope for welfare improvement beyond symptom management. Early trial results are promising but long-term efficacy and safety data are still accumulating. The ideal welfare outcome is a treatment enabling horses to live rug-free without suffering.